1. Field of the Invention
The present invention relates to an image display using an organic electronic luminescent (EL) element, for example, and more particularly to an image display capable of decreasing an amount of electric current per unit pixel with a low cost.
2. Description of the Related Art
Conventionally proposed image displays employing an organic EL element utilize a function of the organic EL element which emits light by recombining positive holes and electrons injected into a light emitting layer thereof.
Such image display includes, for example, a plurality of pixel circuits arranged in a matrix, a signal line driving circuit which supplies a luminance signal described later through a plurality of signal lines, and a scanning line driving circuit which supplies a scanning signal to the pixel circuits through a plurality of scanning lines for selection of a pixel circuit to which a luminescence signal is to be supplied.
FIG. 9 is a side view of a structure of a conventional image display 1. The image display shown in FIG. 9 includes on a glass substrate 2, an anode metal layer 3, a light emitting layer 41, a connection layer 51, a light emitting layer 42, a connection layer 52, a light emitting layer 43, and a cathode metal layer 6 sequentially stacked in this order. A power source 7 is connected between the anode metal layer 3 and the cathode metal layer 6 under control by a control circuit not shown. The light emitting layers 41 to 43 are electrically connected in series and correspond with the organic EL elements mentioned above, respectively.
In the above described structure, when the anode metal layer 3 and the cathode metal layer 6 are connected to the power source 7, the light emitting layers 41 to 43 each emit light. Thus, the conventional image display 1 can enhance the luminance per pixel unit and reduce the amount of electric current per unit pixel by employing the structure where the light emitting layers 41 to 43 are stacked one on another with the connection layers 51 to 52 interposed therebetween.
One of the conventional displays as described above is disclosed in A. Matsumoto et al., IDW' 03, pp. 1285.
Though the conventional image display 1 is advantageous in enhancing the luminance per pixel unit and reducing the amount of electric current per pixel unit by employing the layer of light emitting layers 41 to 43 stacked one on another, the increase in the number of stacked layers also results in the increase in the number of manufacturing processes as well as the manufacturing cost.